1. Field of the Invention
The present invention relates to a semi-conductor laser array in which plural semiconductor laser elements are monolithically formed on a same substrate.
2. Related Background Art
In the conventional semiconductor laser array, as shown in FIG. 1, stripe electrodes 61d-65d are formed in parallel manner, respectively in current injection areas 61a-65a of semiconductor laser elements 61-65. These stripe electrodes are independently connected to a power source by wire bondings 20.
For the purpose of reducing the pitch of the elements in such semiconductor laser array, in case of two elements, the wire bondings are made on both sides of two current injection areas as shown in FIG. 2. Also in case of three or more elements, there is employed three-dimensional wiring as shown in FIG. 3.
However, if the pitch of the semiconductor laser elements in such array becomes smaller than for example the effective width of the wire bonding, which is about 100 .mu.m, the wire bonding operation has to be conducted very precisely and therefore the electrodes can become very easily shortcircuited. Also the wire bonding, if conducted on the current injection area of the laser, may cause damage in the laser element. Such damage may shorten the service life of the laser element or deteriorates the electrical properties, thus eventually destructing the laser element and lowering the production yield.
Also in three-dimensional wiring, the electrodes are often shortcircuited due to through holes in the insulating film or destruction of the insulating film caused by the impact at the wire bonding, so that the production yield is lowered.
Thus, in the conventional laser array with three or more laser elements with the pitch of elements equal to or smaller than 100 .mu.m, it has been difficult to achieve independent driving of the semiconductor elements, or to achieve a high level of integration of the semiconductor laser element, and such laser array has been associated with a low production yield at the mounting.